The present invention generally relates to transportation vehicles such as railroad hopper cars which transport and releasably hold product therein and, more particularly, to an assembly for closing a pneumatic discharge outlet on such vehicle.
Railroad hopper cars typically include an underframe for supporting a walled enclosure in which bulk materials are held and transported. As is conventional, the underframe of the railroad car is supported toward opposite ends by well known wheeled trucks which ride on tracks or rails. A bottom of the walled enclosure is usually provided with two or more individual openings for allowing bulk materials to be discharged from the walled enclosure. The walled enclosure of the railroad car furthermore typically includes sloped or slanted walls or sheets angularly extending upwardly from a periphery of each opening to promote gravitational movement of the bulk material toward the opening.
In the prior art, combination gravity and pneumatic gate structures have been provided which permit the discharge of material from the walled enclosure of a hopper car either by gravity or pressure differential such as vacuum. Such a gate structure typically includes a frame arranged in registry with an opening on the hopper car and a gate which is positioned beneath the opening on the hopper car for movement along a predetermined path of travel. The gate is typically mounted for sliding movement on the frame between open and closed positions. Most gate assemblies include a gate drive mechanism typically in the form of an operating shaft assembly extending laterally across one end of the gate assembly for operationally moving the gate between open and closed positions. In most gate designs, the operating shaft assembly combines with a rack and pinion assembly to move the gate depending upon the rotational direction of the operating shaft assembly. In some gate designs, such a rack and pinion assembly includes a pair of elongated stationary racks projecting in parallel relation relative to each other away from the frame and which intermesh with pinions mounted on the operating shaft assembly. The pinions on the operating shaft assembly are operably connected to and move with the gate. When in an open position, the gate allows the commodity to gravitational pass and be discharged from the hopper car.
At the railroad car unloading station, a powered driver is moved into driving engagement with one end of and turns the operating shaft assembly. As such, the pinions move along the stationary racks, thus, moving the gate therewith. As is conventional, the drivers which impart rotational movements to the operating shaft assembly are mounted on wheels and are readily movable in a direction extending generally parallel to a longitudinal axis of and are movable toward and away from the operating shaft assembly, as required. Such drivers, however, are typically not designed or configured to move sideways along with the gate. Accordingly, as the operating shaft assembly is rotated, the driver is forcibly pulled along in a direction opposed to its natural direction in which the driver moves thereby adding to the forces which must be overcome in moving the gate along its predetermined path of travel.
In the event pneumatic discharge of material is desired, a pan element is positioned underneath the discharge opening and below the gravity gate. Typically, the pan is provided with an open ended outlet tube for discharging the material from the hopper car. The pan is typically fastened to the walled enclosure of the hopper car as with a plurality of fasteners. As will be appreciated, however, valuable time is consumed and lost by having to affix and remove the pan from the hopper car depending upon whether a gravitational discharge mode or a pneumatic mode of discharge is to be used to unload the hopper car. Mounting the pan element beneath or under the gate also reduces the clearance between the bottom of the gate assembly and the railbed over which the car travels between locations. As will be appreciated by those skilled in the art, the degree of clearance between the underside of the gate assembly and the railbed is a serious concern when designing discharge gate assemblies for hopper cars coupled with customer pressures to increase the volumetric payload for the railroad car.
Mounting and arranging the pan element above the sliding gate of the gate assembly has not proven feasible for several reasons. Mounting and arranging the pan element above the sliding gate of the gate assembly has been found to obstruct the flow of material from the walled enclosure in a gravitational mode of material discharge. Mounting the pan element above the gate also presents a problem involving keeping exhaust tubes extending from the pan element clean during loading of the commodity into the hopper car. Furthermore, the moisture in the commodity, tends to cause mold, mildew and other contaminants to be present within outlet tubes leading from the pan element.
The open end of the outlet tube presents still further problems involving railroad hopper car gate assemblies. As will be appreciated, and during transport of the railcar between locations, the outlet tube presents a conduit for directing debris to an interior of the pan assembly. Various devices have been proposed for closing the free open end of such outlet tubes. Such devices, however, often become separated from the outlet tube and are lost. Moreover, the capability of such devices to adequately seal the free open end of the outlet tube is limited. The mechanisms used to secure such known devices to the free end of the outlet tube furthermore add to problems involving timely opening of the discharge tube when pneumatic unloading is the desired means for unloading the railroad hopper car.
Movably mounting a pan element on the frame of the gate assembly beneath the gate introduces significant design problems. First, mounting a pan element for movement beneath the gate requires a second drive mechanism which, most likely, will include another or second operating shaft assembly along with a rack and pinion assembly. As will be appreciated, providing a second drive mechanism for moving the pan element relative to the frame structure of the gate assembly seriously complicates the gate design in several respects. First, the provision of two independently operable drive mechanisms complicates the process for emptying the lading from the hopper car. Second, spacial requirements for the gate assembly, especially when considering the drive mechanism for moving the gate between open and closed positions, is severely restricted. Providing an additional or second drive mechanism on the frame of the gate assembly for moving the pan element between open and closed positions can further adversely effect the clearance required between the gate assembly and the railbed. Of course, if the gate assembly does not provide proper clearance significant damage can result to the gate assembly and the car as the railcar moves between locations. Simply raising the gate assembly, however, reduces the potential volumetric payload capacity of the car while also raising the railcar""s center of gravity. Moreover, the addition of a second drive mechanism complicates the direction in which each drive mechanism is to be turned or rotated to effect movement of a particular element on the hopper car gate assembly.
The transportation and unloading of finely divided materials, and particularly food stuffs, such as sugar, flour and the like within and from the walled enclosure of the hopper car exacerbates the problems involved with the design and engineering of a railroad hopper car discharge gate assembly. When the material to be transported involves food stuffs, the FDA has promulgated certain rules and regulations which must be met in order for the hopper car to qualify for transporting foods stuffs. Of course, one of the paramount concerns involved in designing the hopper car discharge gate assembly is that no foreign matter, accumulation of moisture, or insect infiltration is permitted to contact and possibly contaminate the food stuffs even while they are being discharged or unloaded from the hopper car.
When only gravitational discharge of the hopper car carrying food stuffs is to be effected, the frame of the gate assembly or structure is usually provided with a flanged skirt depending from and arranged in surrounding relation relative to an opening defined by the frame of the gate assembly. The flanged skirt defines a discharge plenum. Typically, an air sled or other form of unloading apparatus is clamped to the flange on the skirt during a gravitational discharge operation of food stuffs thereby permitting the food stuffs in the hopper car enclosure to be discharged directly and protectively into the sled and, thus, conveyed away from the hopper car.
To inhibit debris, insects, moisture, clay and other forms of debris from contaminating the underside of the gate and interior of the discharge plenum during transport of the hopper car, such gate assemblies typically include a sanitary plate or cover element positioned beneath the gate to close the discharge plenum and protect the underside of the gate during transport of the hopper car. Of course, known sanitary plates or cover elements are neither designed nor configured to withstand the load which can be placed thereon by the materials within the enclosure of the hopper car.
As they travel between locations, railroad cars are subjected to numerous impact forces, some of which are quite severe. For example, when a railroad car moves down a hump in a classification yard it likely will impact with other railroad cars on the track ahead of it and such impacts can be exceedingly forceful. While shock absorbers are typically built into the coupling units on the railroad cars, still there are sever shock loads within the body of the car and its contents. Of course, when the railroad hopper car is fully loaded, the impact forces are multiplied to even higher levels than with other railroad cars. Such shock loads can affect the position of either gate assembly element, i.e., the slide gate and/or the pan assembly, due to the inertia of either or both elements.
Accordingly, the gate assembly design can furthermore be complicated by requiring a lock assembly for inhibiting the sliding gate from inadvertently moving toward an open position. When the gate assembly embodies a movable pan element underneath the gate, the gate assembly design is furthermore complicated by requiring still another lock assembly for inhibiting inadvertent movement of the pan element toward an open position.
As will be appreciated by those skilled in the art, known slide gate systems can have relatively large gates to effect rapid discharge of materials from the hopper car enclosure. Especially with larger size gates, the column of material above the gate assembly presents a significant downwardly acting force on the gate. This downwardly acting force has been known to cause the gate to bow or curve under the influence of the downwardly acting force. A proper gate assembly design should allow the mechanism used to open the gate to act rapidly and with consistency without requiring an abundant amount of torque to be applied to the drive mechanism to move the gate from a closed position or condition toward an open position or condition.
Thus, there is a continuing need and desire for a hopper car discharge gate assembly which allows for either gravitational or pneumatic unloading of material from the walled enclosure with relatively easy change over thereby adding to the versatility of the hopper car. Moreover, it is desirable to provide a discharge gate assembly having two readily movable elements controlled by separate drive mechanisms while maintaining adequate clearance between a lowermost surface on the gate assembly and the railbed. Additionally, the gate assembly should be designed to provide a lock for each element of the gate assembly thereby inhibiting inadvertent movement of either element toward an open position as a result of impact forces acting on the railroad car. Furthermore, an improved apparatus for closing and sealing the free open end of the outlet tubes used during pneumatic withdrawal of the lading from the hopper car is desired
In view of the above, one of the salient features of the present invention involves provision of a gate assembly for a railroad hopper car which can be readily and easily conditioned for either pneumatic discharge or gravitational discharge of materials therethrough. The gate assembly of the present invention includes a rigid frame defining a discharge opening and which is provided with a gate or first element slidably carried on the frame for controlling the discharge of material from the hopper car and through the discharge opening. The gate assembly of the present invention is also provided with a second slidable element carried by the frame and extending across the discharge opening. The first and second elements of the gate assembly are arranged in vertically spaced relation relative to each other. In a preferred form, the first and second elements of the gate assembly are disposed in generally parallel relationship relative to each other. A first drive mechanism including a first operating shaft assembly is mounted on the gate frame for slidably moving the first element relative to the frame. A second drive mechanism including a second operating shaft assembly is also mounted on the gate frame for slidably moving the second element relative to the gate frame. One of the salient features of the present invention relates to arranging each of the operating shaft assemblies on the gate frame for rotation about independent fixed axes and in horizontally adjacent relation relative to each other.
In a preferred form, the frame of the gate assembly preferably has a rectangular configuration. That is, the frame is preferably configured as a four sided rigid structure including a pair of generally parallel side walls extending generally parallel to a longitudinal axis of the railroad car on which the gate assembly is mounted and a pair of end walls rigidly interconnected to the side walls. Preferably, each of the operating shaft assemblies extend generally parallel to an end wall of the frame structure. In a preferred form, the side walls and end walls each define angularly diverging surfaces extending upwardly from the discharge opening toward an upper surface of the frame structure.
The first and second drive mechanism each preferably include a rack and pinion assembly arranged in operable combination with the operating shaft assembly of the respective drive mechanism. Each rack and pinion assembly includes a rack operably associated with a respective element. Pinions mounted on each operating shaft assembly are arranged in intermeshing relationship relative to the racks. Moreover, each rack is movable along a predetermined path of travel concomitantly with movement of the respective element. In a preferred form, the racks of each rack and pinion assembly extend generally parallel to a side wall of the frame structure.
To operate either operating shaft assembly, a driver is typically inserted into operative combination with that operating shaft assembly operably associated with the element on the gate assembly desired to be moved. It is common for such a driver to be telescopically inserted into an appropriately configured drive end opening provide on the operating shaft assembly. The configuration of each drive end opening on the operating shaft assembly, however, can quickly and adversely change as a result of the relatively high impact forces and torque applied thereto by such drivers, thus, requiring repair and/or replacement of the operating shaft assembly.
Accordingly, each operating shaft assembly forming part of the gate assembly of the present invention is preferably of multipiece construction. That is, each operating shaft assembly preferably includes a rotatable shaft and capstans removably attached at opposite ends of the shaft. Such multipiece construction readily allows repair and/or replacement of any component part in a cost efficient and effective manner without having to replace an entire assembly. Such multipiece construction furthermore allows repair and/or replacement of one or more components of the operating shaft assembly without having to remove the entire operating shaft assembly from operable association with the remainder of the gate assembly.
In a preferred form, the axes of the first and second shaft assemblies are mounted to a common vertical side of the predetermined path of travel of the racks. Accordingly, and to simplify operation of the operation of the gate assembly, the operating shaft assemblies operate in the same or common directions to open the first and second elements of the gate assembly and in the same or common direction to close the first and second elements of the gate assembly of the present invention.
To reduce the amount of torque required to be applied to the first and second operating shaft assemblies in moving their respective element relative to the frame, the racks of each rack and pinion assembly are elevationally spaced from that portion of the frame supporting same. In a most preferred form, ultra-high molecular weight polyethylene material is disposed between the racks and the frame to significantly reduce the coefficient of friction therebetween as the first and second elements move between open and closed positions.
The first element of the gate assembly is preferably configured as a generally planar gate which slidably moves in a generally horizontal direction between open and closed positions in response to rotation of the first operating shaft assembly. The second element of the gate assembly is preferably configured as an open top pan assembly having a hood extending thereacross and which is mounted vertically and for generally horizontal movements beneath the gate. The pan assembly defines outlet tubes laterally extending from opposed sides thereof and to which a suction hose or the like is attached to effect pneumatic discharge of materials from the hopper car.
According to another aspect of the present invention, end caps are provided at the open end of each outlet tube of the pan assembly. Unlike heretofore known end cap structures, however, the end caps of the present invention are each affixed to the free ends of the outlet tubes on the pan assembly to advantageously allow for one-handed unlocking/opening and locking/closing of the end cap relative to the outlet tube or discharge outlet. A gasket or seal is preferably arranged in combination with the end cap and the outlet tube on the pan assembly to furthermore inhibit passage of contaminants and moisture into the material receiving portion or chamber of the pan assembly. To provide a substantially equally distributed force against the seal as the end cap or cover is moved to the closed position, cams are preferably arranged in combination with each end cap thereby enhancing closure of the end cap relative to the outlet tube on the pan assembly.
In a preferred form, the racks of the rack and pinion assemblies arranged in operative combination with the gate and pan assembly are each disposed to opposed lateral sides of the gate and pan assembly in locations outwardly removed from beneath the discharge opening. In a most preferred form of the invention, the racks of each rack and pinion assembly are arranged outside or to opposed lateral sides of the discharge opening defined by the frame structure of the gate assembly. This preferred gate assembly design readily lends itself to improved sealing capabilities between the gate as well as the pan assembly and the frame structure thereby inhibiting debris and moisture from contaminating the materials held and transported within the hopper car.
As will be appreciated by those skilled in the art, a significant weight is applied to the gate extending across the discharge opening by the materials maintained and transported within the hopper car. The weight of such materials often causes distortion of the gate which complicates sliding of the gate, at least, between closed and open positions. In view of the above, a preferred form of the present invention contemplates providing a stationary support across the discharge opening for inhibiting the gate from bending beyond a predetermined limit. As with the racks of the gate assembly, in a preferred embodiment, ultra-high molecular weight polyethylene material is disposed between the support and the undersurface of the gate to promote sliding movements therebetween. A stationary deflector or hood including angularly diverging sides is also provided above the discharge opening defined by the frame assembly to address the significant weight provided by the lading in the hopper car pressing downwardly onto an upper surface of the gate.
A preferred design of the present invention furthermore embodies a tamper seal arrangement allowing for application of a tamper seal in combination with the gate assembly. As is conventional, the tamper seal, when arranged in combination with the gate assembly, readily provides a visual indication of whether the gate has been moved to provide unauthorized access to the materials contained within the hopper car.
To address the problems and concerns associated with inadvertent movements of the gate assembly elements relative to the frame structure, a preferred embodiment of the gate assembly further includes a lock assembly. The lock assembly associated with the gate assembly of the present invention includes a lock which, when the gate is in a closed position, inhibits inadvertent movement of the gate toward an open position. A preferred embodiment of the lock assembly further includes a second lock which, when the pan assembly is in a closed position, inhibits inadvertent movement of the pan assembly toward an open position. In a most preferred form of the invention, both the lock for maintaining the door in a closed position and the lock for maintaining the pan assembly in a closed position are incorporated into a single mechanism, thus, eliminating the need for and operation of two separate lock assemblies.
When the gate assembly of the present invention is mounted to a railroad hopper car, the design advantageously allows for either pneumatic discharge or gravitational discharge of material from the hopper car. As a commodity filled railcar travels between locations and then is parked waiting to be unloaded, the lock assembly ensures the gate and the pan assembly will remain in their closed condition even though significant impacts may be applied to the railcar as it travels or awaits discharge of the materials therefrom.
Arranging the first and second operating shaft assemblies for the two movable elements of the gate assembly for rotation about fixed axes and in horizontally adjacent relation relative to each other offers several meritorious design advantages. The arrangement of the operating shaft assemblies according to the present invention minimizes the vertical distance or height between the upper attaching surface of the gate assembly and the lowermost surface of the pan assembly while retaining an adequate angle on the sidewalls and end walls to assure materials discharge from the hopper car and through the discharge opening. Of course, minimizing the distance the gate assembly depends from the hopper car allows added clearance beneath the hopper car while allowing for greater volumetric payload capacity. Furthermore, arranging each operating shaft assembly to rotate about a fixed axis eliminates cumbersome, longitudinal readjustment of the powered drivers which are common at unloading sites across the country.
Another object accomplished by a preferred form of the present invention relates to operating the operating shaft assemblies in a common direction to open and close the elements operably associated with each operating shaft assembly, thus, reducing human operator confusion of open and closure directions.
Another object of the present invention involves providing a railroad hopper car gate assembly having two elements which are independently movable between open and closed positions through operation of independently operable shaft assemblies, each of which rotates about a fixed axis, thereby advantageously permitting an operator to independently operate the gate elements while concurrently validating cleanliness of the commodity contacting surface areas on the elements as they move between positions.
Still another object of this invention is to simplify operation of the end cap or cover associated with the discharge port of the open top pan assembly.
Another object of this invention is to provide a closure cap assembly for the pan assembly which provides a substantially equally distributed force to the seal or gasket used in combination therewith as the closure cap moves toward the closed position.
These and other objects, aims and advantages of the present invention will be readily and quickly appreciated from the following detailed description, appended claims, and drawings.